Two Techniques for Thinning Grape Inflorescences
A grape inflorescence may contain 300-1500 flowers, and most of the flowers and berries will drop during fruit set. Therefore, thinning the inflorescences retained on the fruiting canes can strengthen the development of the remaining flowers. 1. Removing inflorescences. This refers to removing the entire inflorescence from the fruiting cane. When the vine has a heavy crop load and too many inflorescences, it is necessary to...
A grape inflorescence may contain 300-1500 flowers, and most of the flowers and berries will drop during fruit set. Therefore, thinning the inflorescences retained on the fruiting canes can strengthen the development of the remaining flowers.
1. Removing inflorescences. This refers to removing the entire inflorescence from the fruiting cane. When the vine has a heavy crop load and too many inflorescences, thinning is needed. Remove poorly developed, weak, small inflorescences and those that are too densely distributed or improperly positioned, so that nutrients are concentrated on supplying the superior inflorescences that remain. Besides the overall crop load of the vine, the growth vigor of the fruiting canes must also be considered. Vigorous fruiting canes that bear two or even more clusters can all develop well, and can also serve as superior fruiting mother canes for the next year. Weak, small fruiting canes are not suitable as fruiting mother canes for the next year. Based on domestic and international experience, for table varieties such as Muscat Hamburg and Kyoho, the principle of "2 for strong, 1 for medium, none for weak" can be adopted as a reference when thinning inflorescences; that is, a strong fruiting cane may retain 2 clusters, a medium fruiting cane retains 1 cluster, and a weak fruiting cane should retain as few inflorescences as possible. Thinning inflorescences can be combined with bud rubbing and shoot removal, or, on the basis of shoot removal, carried out from before flowering to the flowering stage; from the standpoint of saving nutrients, it is better to do it as early as possible.
2. Pinching the cluster tip and shaping the inflorescence. This is generally achieved by pinching the tip of the inflorescence and shaping the inflorescence. Usually it is not individual flowers that are removed, but the branch axes of the various orders within the inflorescence (the spikelets). Pinching the cluster tip and shaping the inflorescence should preferably be done within one week before flowering. If too late, the effect of promoting fruit set is poor; if too early, the inflorescence is not sufficiently extended and shaping is rather inconvenient. As for the degree of pinching the cluster tip, for Muscat Hamburg and Kyoho, generally about 1/4-1/5 of the inflorescence length is pinched off. Pinching the cluster tip not only achieves the purpose of thinning out some of the flowers, but also reduces the risk of soft tips or water-berry disease at the tip of the cluster.